Rate of cijmb indicator



Mayll, 1937. HORN RATE OF CLIMB INDICATOR Originaly Filed Sept. 9,' 1955*' Ressued May 11, 193.7

UNITE-o STATES PATENT OFFICE yOriginal N0. 2,056,354,

Serial N0. 39,822, September 9, 1935.

dated October 6, 1936,

Application for eissue March 3, 1937, Serial No. 128,873. In Germany September 22, 1934.

3 Claims.

'I'his invention relates to a device vrfor indicating the climbing speed and rate of vertical descent of `an aircraft.

The object of the invention is the provision of a device of this character in which the indicating pointer .is instantaneously responsive to variations in the ascent and descent of aircraft.

According to the invention the measuring principle is based on the measurement of the pressure difference produced during the ascent and descent of the aircraft, between the outside air and the air contained in a vessel in communicanon with the outside airthrough a smallV orifice.4

The measurement of this pressure difference is not, however, eiected by means ofv a diaphragm box as in prior types of rate of climb indicators, but by means of a pressure plate instrument.

In the accompanying drawing wherein an improved embodiment of the invention is illustrated, M

Figure 1 is a front elevation of the indicator with parts removed.

Fig. 2 a transverse section through the indicator showing the connection of the latter with an air reservoir. v

Fig. 3 is a perspective view of the indicator removed from the housing and showing the internal parts thereof. f g' Referring to the drawing in detail a designates an air reservoir of approximately half a liter capacity which is protected against the influences of changing temperature by the well known double walled covering.

The reservoir a is connected by a pipe b with a circular air chamber c provided in the body c1 of the indicating device, the open top of the chamber being normally closed by a cover cz. y A pressure plate f rigidly secured to the supporting shaft i is located in the air chamberc and is normally held in a predetermined position by a spring k.

The shaft i is mounted to freely rotate in bearings g and.,h provided respectively in the body c1 and a bearing arm o supported thereby. 'I'he cover c2 is provided with an opening p through which the shaft i passes and a pointer m is rigidly secured to the shaft i'and is movable over the 'plate n having the usual graduated scale thereon.

The body c1 is provided internally with a sector-shaped partition vwall l extending from4 the annular wall of the chamber cinto close relation to the shaft i, the wall l being disposed opposite to the normal position of the pressure plate f.

The portion of the chamber c at one side of the pressure plate f communicates with a port d,

which, as above stated, is in communication with the reservoir a. through the pipe b. At the opposite side of the pressure plate f, the'chamber c is in communication with a port e communicating with the outside air. 5

The shaft i is located at the center of the circular chamber c and the pressure plate f is of such dimensions as to provide a clearance space or capillary gap of about one-tenth millimeter on all sides thereof between it and the walls of said chamber. Approximately the same clearance space is ailorded between the shaft i and the partition wall l.

When the aircraft ascends, the atmospheric pressure decreases in accordance with the rate of climb ofthe aircraft. Theair contained in the reservoir a, therefore, flows outwardly therefrom and since it can only follow the path over the clearance space or gap between the wall of the. chamber c and the pressurevplate f, said plate `is moved against the tension of the spring k to an extent corresponding to the velocity of the air which, as will be understood, depends upon the prevailing difference between the air in the reservoir and the outside air. y 25 A pressure difference between the air within the reservoir a and the outside air occurs whenever the aircraft ascendsor descends and the equalization of these pressures can only be effected by the passage of air through the space or gap between the pressure plate f and the wall of the chamber, said gap, accordinggto its shape, constituting a iiat plate opening, comparable with a capillary tube. Since, however, said air gap corresponds tov a very wide capillary opening and alsov since the spring k has no lag like that of a diaphragm box, the pointer is adjusted to the measuring value much more quickly than in the known types of rate of climb indicators employing diaphragm boxes.

A further advantage of the improved indicator lies in the fact that the mechanism can withstand substantially any pressure, that is to say, it has an overload capacity as compared with the type of climb indicators having diaphragm boxes.

A further advantage lies in the fact that the pressure plate j and shaft i are of small weight and in the consequent ability of these parts to withstand shocks. y

What is claimed is:- 1. .A rate of climb indicator comprising a thermally insulated reservoir, a circular chamber,- a stationary partition wall arranged in said chamber, a shaft rotatably mounted in the axis of said chamber, a pressure plate rotatable with said shaft in said chamber, spring means normally retaining said pressure plate in predetermined positiorr, means connecting said cham- 5 ber at one side of said pressure plate with said reservoir, means connecting said chamber at the opposite side of said pressure plate with the atmosphere, said pressure platebeing arranged to provide a gap between the edges thereof and the walls of said chamber, the dimensions of said gap being such that it serves as a capillary orice whereby upon occurrence of a pressure difference between the atmospheric air and the air in said reservoir, said plate moves in response to said pressure difference, the ilow of air through said gap causing equalization' of the pressures on the two sides of said plate, and indicating means actuated by movement of said plate and shaft. 2o 2. A rate of climb responsive device comprising a reservoir, a circular chamber, a partition in said chamber, a\shaft rotatably mounted in said chamber, a pressure plate rotatable with said shaft in said chamber, means normally retaining said pressure plate in a predetermined position, means connecting said chamber at one side of said pressure plate with said reservoir, and means connecting said chamber at the opposite side of said pressure plate with the atmos- 30 phere, said pressure plate being arranged to provide a gap between an edge thereof and a wall Cil of said chamber, the dimensions of said gap being such that it serves as acapllary orifice,

`normally retaining said pressure member in a predetermined position, said second chamber being in communication with said rst chamber at one side of said pressure member and in communication with the atmosphere at the other side of' said pressure member whereby a. difference in pressure occurs on the two sides of said member upon a change in altitude, said pressure member forming a capillary gap between an edge thereof and -a wall of said second chamber, whereby said member is actuated upon occurrence of a preure difference on the two sides of said member'dge to a change in altitude and air is caused to flow through said gap to cause equalization of the pressures on the two sides of said member, and indicating means actuated by said pressure member.

ERHARD HORN. 

